Data transmission system and method

Abstract

Data (D) transmission system (10) via satellite (11), comprising at least one satellite station (40) disposed on a respective satellite (11) with which a first transmission station (20) and a second transmission station (30) are operatively connected, during use, wherein at least one of either the first (20) or the second station (30) is disposed, during use, on a mobile means of transport (12), the other being disposed on a respective mobile means of transport (12) or on a fixed point on land. The stations (20, 30, 40) comprise, respectively, at least an optical assembly (22, 32, 42) configured to transmit and / or receive one or more optical signals (SO) comprising at least a first type of optical signal (SOI) to allow the quantum distribution of encryption keys, and a transmission assembly (21, 31, 41) configured to transmit and receive one or more radio frequency signals (SR) containing data (D), wherein said optical assemblies (22, 32, 42) and said radio frequency transmission assemblies (21, 31, 41) are configured to transmit and / or receive respective pointing signals to achieve an alignment between the stations (20, 30, 40).

Description

[0001] “DATA TRANSMISSION SYSTEM AND METHOD”

[0002] FIELD OF THE INVENTION

[0003] The present invention concerns a data transmission system and method via satellite, which guarantee the security of communications and enable autonomous navigation of means of transport, in particular naval transport, whether of small or large sizes, both for passengers and goods. The system is also particularly useful for other applications, for example for the digitalization of ports and maritime systems.

[0004] BACKGROUND OF THE INVENTION

[0005] Recently, particularly in the maritime sector, different technologies have been introduced in order to allow the autonomous navigation of means of freight transport; this has led to the digitalization of many operating procedures, allowing to reduce customs embarkation and disembarkation times, as well as entry and exit times from a port.

[0006] Autonomous navigation, however, is an activity that involves very complex procedures and requires the transmission of large amounts of data via satellite by means of signals exchanged between a first station on the ground, the satellite, and a second station present on the mobile means of transport, for example on the vessel and / or ship.

[0007] Part of this data can be transmitted unencrypted, that is, not coded or encrypted; another part has to be transmitted in an encrypted or coded way, since it contains confidential information that has to be protected against cyber-attacks.

[0008] For this type of information and to guarantee high levels of security for it, specific cryptography techniques are used, in which the encoding and decoding of the transmitted data can only take place through the exchange of encryption keys between sender and recipient.

[0009] Currently, the most widely used cryptography technique is asymmetric cryptography, which has a security level of about 99.5%, and the data encrypted in this way are usually transmitted by means of classic radio frequency communication channels or by means of optical communication systems.

[0010] This cryptography technique has the disadvantage that it does not give the absolute guarantee that an intercepted message cannot be decrypted by third parties, for example through the use of a quantum computer that exploits an efficient key reconstruction process.

[0011] This has led to the development of a key distribution technique for symmetric cryptography based on the quantum properties of light, known as quantum key distribution (QKD) or, more improperly, by the term quantum cryptography. This technique allows to generate symmetric keys through an exchange of photons, or light quanta, that is, through a point-to-point optical connection between sender and recipient. Thanks to the peculiar properties of quantum states, there is a percentage of security of the keys, and therefore of the encrypted data transmitted, of 100%, since any attempt to intercept and reconstruct the key inevitably leaves a trace that can be revealed by the sender and / or the recipient.

[0012] In general, to carry out an exchange of encrypted data with the quantum key distribution technique there must be a stable optical connection between the sending station and the receiving station. However, there may be the drawback that it is not always possible to have a stable and correct connection, in particular when the receiving and / or transmitting station are connected to each other remotely, in the air, and at least one is in motion.

[0013] This drawback is particularly evident when at least one of the stations is located on a satellite in low orbit, where the satellite has a speed of more than 7 kilometers per second, which moves quickly and remains in a zone aligned with the port or with a vessel, which is also in motion, only for limited time intervals, at most of the order of 5-10 minutes.

[0014] Document US 2020 / 0396067 Al describes a control apparatus installed in a ground station able to generate instructions for a satellite, wherein the control apparatus and the satellite comprise an encryption device for encrypting the instructions by means of a quantum key shared with the satellite. US 2020 / 0396067 Al provides to create a connection between the control apparatus and the satellite by means of an optical type pointing signal that is exchanged between reciprocal transmitter and receiver, and emitted at predefined intervals in the case of geostationary satellites or on the basis of information relating to the current and expected position of a satellite in orbit. The solution described in US 2020 / 0396067 Al is however not applicable for establishing a connection between a satellite and a station installed on board a vessel, which is subject to vertical and horizontal wave motions that make it difficult to create effective optical type pointing.

[0015] Document GB 2607557 A concerns a system and method for aligning a quantum laser beam with a receiver by means of optical signals, in particular by generating and transmitting both a classical, that is, non-quantum, laser beam and also a quantum type laser beam. However, this solution is also not applicable for establishing a connection between a satellite and a station installed on board a vessel which is subject to vertical and horizontal wave motions.

[0016] There is therefore the need to perfect a data transmission system that can overcome at least one of the disadvantages of the state of the art.

[0017] To do this, it is necessary to solve the technical problem of providing a system and perfecting a method for data transmission via satellite that are 100% secure and that allow to achieve an effective connection and stable communication even when the transmitting and / or receiving station are moving.

[0018] In particular, one purpose of the present invention is to provide a system and perfect a method for data transmission that are optimized for the autonomous driving and the digitalization of maritime systems, which are safe and effective against possible cyber-attacks.

[0019] Another purpose of the present invention is to provide a system and perfect a method for data transmission that can lead to an economic benefit in relation to the operation of the means of transport.

[0020] Another purpose of the present invention is to provide a system and perfect a method for data transmission that allow to improve safety during the operation of the means of transport.

[0021] Another purpose of the present invention is to provide a system and perfect a method for data transmission that guarantee correct pointing and connection between satellite stations on one end, and stations located on means of transport, and therefore in motion, on the other.

[0022] The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

[0023] SUMMARY OF THE INVENTION

[0024] The present invention is set forth and characterized in the independent claims. The dependent claims describe other characteristics of the present invention or variants to the main inventive idea.

[0025] In accordance with the above purposes and to resolve the technical problem described above in a new and original way, also achieving considerable advantages compared to the state of the prior art, a data transmission system via satellite according to the present invention comprises at least one satellite station disposed on a respective satellite, at least a first transmission station and at least a second transmission station, wherein at least one of either the first or the second station is disposed, during use, on a mobile means of transport, in particular a vessel, the other of said stations being disposed, during use, on a respective mobile means of transport or on a fixed point on land.

[0026] Preferably, the mobile means of transport can be a vessel, such as a freight or passenger ship, the fixed point on land can correspond to a seaport, although the application of the transmission system to means of transport such as trains or planes is not excluded; in this case, the fixed point could correspond to a station or airport.

[0027] In accordance with one aspect of the present invention, the first and second station and the satellite station each comprise: at least one radio frequency transmission assembly configured to transmit and receive one or more radio frequency signals containing the data, at least one optical assembly configured to transmit and / or receive one or more optical signals comprising at least a first type of optical signal to allow the quantum distribution of encryption keys, and at least one management and control unit of the radio frequency transmission assembly and of the optical assembly, the management and control unit being configured and programmed to generate the encryption key with a quantum key distribution protocol and to associate the at least one encryption key with at least a part of the data to encrypt them and, respectively, decrypt them when they are transmitted and, respectively, received between one station and another.

[0028] Doing so achieves at least the advantage that the data is encrypted with an encryption key distributed with the quantum key distribution protocol, thus enabling autonomous and completely secure navigation of the means of transport and, if applied to the maritime sector, also a digitalization of maritime systems to guarantee the secure exchange of sensitive information, such as the bill of lading. In accordance with the present invention, the management and control units of the at least one satellite station and the first and second station are configured and programmed to command the respective radio frequency transmission assemblies so as to transmit or, respectively, receive a first radio frequency pointing signal to establish a first alignment between one of the first and / or second station and the at least one satellite station, and subsequently command the respective optical assemblies to transmit and receive at least a second type of optical pointing signal, in order to establish a stable point-to-point optical connection between the first and / or second station and the at least one corresponding satellite station.

[0029] Thanks to this solution, it is possible to achieve an effective alignment and pointing between the first and / or second station and the satellite station, and vice versa, not only when the first or second station are installed in a fixed point on land, but also when they are installed on board mobile means of transport, that is, means of transport that need to exchange quantum encryption keys with the satellite station even when they are moving.

[0030] This solution also allows to punctually align and connect stations installed on ships and vessels that are subjected to sudden movements in the vertical and horizontal direction given by the waves, since thanks to the two-step procedure it is possible to first obtain a rough alignment thanks to the radio frequency signal that requires less precision and subsequently, based on the first alignment, it is possible to transmit a second optical type signal so as to obtain a precise and punctual pointing that yields two benefits: on the one hand, it allows for an effective exchange of the first optical quantum signal, and on the other, it allows to maintain contact between the two systems for longer and therefore to exchange a greater quantity of data.

[0031] The system according to the invention can comprise a plurality of satellite stations, each associated with a satellite, which during use are orbiting around Earth, and a plurality of first and second stations associated with the Earth, wherein the first stations can be fixed stations, that is, installed in respective buildings or properties, for example in the vicinity of a port, while the second stations can each be installed on board a respective vessel, or ship, or vice versa. However, it can be provided that both the first as well as the second station are installed on respective means of transport, so as to allow direct communication between them, or that both are installed in fixed points.

[0032] According to one aspect of the invention, each first station, second station and satellite station is configured to transmit and receive both one or more radio frequency signals containing the data relating to the information that has to be exchanged and transmitted between such stations, and also one or more radio frequency pointing signals having the purpose of establishing a first connection with a satellite station or one between the first or second station.

[0033] The radio frequency pointing signals can be signals with predefined characteristics, different from those of the radio frequency signals used for data transmission, which make them distinguishable from the latter and therefore recognizable by the respective transmission / reception assemblies for their specific function.

[0034] According to another aspect of the invention, each first station, second station and satellite station is configured to transmit and receive at least one optical pointing signal to establish a stable point-to-point optical connection with the satellite station or one of either the first or second station, respectively, and possibly to transmit and / or receive an optical signal to allow the quantum distribution of encryption keys.

[0035] Advantageously, the combined use of radio frequency signals and optical signals allows to be able to rapidly establish stable communication between the first or second stations and the satellite stations, or vice versa, since the radio frequency signals allow to achieve a first rough alignment between two respective stations which allows to speed up and facilitate the point-to-point alignment required for the optical signals. Furthermore, this allows to keep the connection between the stations for a longer period of time, even 8-10 minutes, and therefore to cover a much larger area than a transmission system that is completely based on optical transmissions, thus guaranteeing a timelier temporal coverage, with the same number of satellite stations, and further economic savings.

[0036] In accordance with another aspect of the present invention, the transmission of the first type of optical signal is unidirectional, from the satellite station toward the first or second station.

[0037] In particular, the transmission of the first optical signal is carried out by a third optical assembly present in a corresponding satellite station toward a first or second optical assembly present in the first and second station, respectively.

[0038] In accordance with another aspect of the present invention, by transmitting the first type of optical signal, the satellite station and the connected first or second station are able to co-generate a shared encryption key, subsequently used to encrypt, or decrypt, the data.

[0039] In accordance with another aspect of the present invention, each optical assembly is configured to also transmit and receive a second type of pointing optical signal, spatially aligned with the first type of optical signal, to establish a stable point-to-point optical connection between a respective one of the first or second station and a corresponding satellite station, or vice versa. In particular, the transmission of the second type of optical signal is bidirectional, from the satellite station to the first and / or second station, and vice versa.

[0040] In accordance with another aspect of the present invention, each satellite station comprises a third management and control unit provided with at least one automatic generation sub-unit configured to manage the quantum key distribution protocol and the consequent generation of encryption keys able to be stored in a memory, or used one at a time to encrypt the data and send them by means of the radio frequency signal. The same keys, once encrypted with other encryption keys, can also be sent, by means of the radio frequency signal, to thus make them usable by the respective first and / or second management units of the first and second station, for example according to the trusted-node scheme. The memory is able to store a large number of encryption keys, even greater than 100,000.

[0041] In accordance with another aspect of the present invention, in the first and second station there are provided respective electric management means, such as computers, processors or suchlike, connected to the first and second management and control unit, respectively, and having a management interface able to be possibly commanded by a user, either directly or remotely.

[0042] In accordance with another aspect of the present invention, each radio frequency transmission assembly comprises at least a plurality of antennas suitably oriented in such a way as to cover an area sufficiently wide to allow the correct transmission of the radio frequency signals, and at least one transceiver module having an adequate frequency channeling so that it can be tuned in to different sources and frequencies. The number, size and properties of the antennas can be the same or different depending on the station on which they are installed.

[0043] In accordance with another aspect of the present invention, each optical assembly comprises respective means for generating and means for propagating the optical signals.

[0044] The generating means comprise at least one emitter, one or more intensity modulators, one or more phase modulators and an attenuator which are operatively connected to each other. The optical propagation means comprise at least one main lens, at least one rapid orientation mirror and a dichroic filter to direct the optical signals to a dedicated camera and / or telescope, which allow to transmit the optical signals through the atmosphere toward a specific destination zone.

[0045] The present invention also concerns a method for transmitting such data executed by means of this transmission system.

[0046] The method comprises one or more operating steps in which respective radiofrequency transmission assemblies of the first and second station and of the satellite station transmit and receive one or more radiofrequency signals containing the data, in which respective optical assemblies of the first and second station and of the satellite station transmit and / or receive one or more optical signals comprising at least a first type of optical signal for the quantum distribution of encryption keys, and in which respective management and control units of the first and second station and of the satellite station associate the at least one encryption key with at least a part of the data in order to encrypt and, respectively, decrypt them when they are transmitted and, respectively, received between one station and another. In particular, the data transmission occurs between one and the other of the first and second station by means of the satellite station, which acts as an intermediary.

[0047] In accordance with another aspect of the present invention, the radio frequency transmission assemblies of two of the stations transmit and / or receive a first radio frequency pointing signal to establish a first alignment between them, and, subsequently, the respective optical assemblies also transmit and receive at least a second type of pointing optical signal, which is aligned with the first type of optical signal, to establish a stable point-to-point optical connection between the first and / or second station and a corresponding satellite station. In accordance with another aspect of the present invention, the first type of optical signal is transmitted in a unidirectional manner from the satellite station toward one or each of the first and second station. In particular, the first type of optical signal is transmitted only from a third optical assembly present in a corresponding satellite station toward a first or second optical assembly present in the first and second station, respectively.

[0048] The type of optical signal is bidirectional, both from the satellite station toward the first and second station and also from the latter toward the satellite station. In particular, the second type of optical signal is transmitted both from the third optical assembly toward the first and / or second optical assembly, and also from the latter toward the third optical assembly.

[0049] In accordance with another aspect of the present invention, by means of the transmission of the first type of optical signal, the satellite station and the connected first or second station, through the quantum encryption key distribution protocol, co-generate an encryption key subsequently used to encrypt, or decrypt, the data.

[0050] In accordance with another aspect of the present invention, a processing subunit of the management and control unit manages the quantum distribution protocol of encryption keys which are stored in a memory, or transmitted one at a time together with the encrypted data by means of the radio frequency signal, in order to thus make them usable for the respective first and / or second management unit of the first and second station.

[0051] In accordance with another aspect of the present invention, the data are transmitted through the one or more radio frequency signals according to three different modes:

[0052] - a first mode, in which each data transmission occurs with an associated encryption key distributed with a quantum distribution protocol and having the same size as the data transmitted;

[0053] - a second mode, in which an encryption key is distributed with a quantum distribution protocol periodically, and is used to encrypt communications which follow the distribution using a standard security protocol until a new encryption key is available;

[0054] - a third mode, in which the data is encrypted with an asymmetric encryption key, therefore using a standard communication channel without using encryption keys distributed with a quantum key distribution protocol.

[0055] DESCRIPTION OF THE DRAWINGS

[0056] These and other aspects, characteristics and advantages of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

[0057] - fig. 1 is a schematic representation of a data transmission system via satellite according to the present invention;

[0058] - fig. 2 is a schematic representation of a transmission station of the transmission system of fig. 1.

[0059] We must clarify that the phraseology and terminology used in the present description, as well as the figures in the attached drawings also in relation as to how described, have the sole function of better illustrating and explaining the present invention, their purpose being to provide a non-limiting example of the invention itself, since the scope of protection is defined by the claims.

[0060] To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can be conveniently combined or incorporated into other embodiments without further clarifications. DESCRIPTION OF SOME EMBODIMENTS OF THE PRESENT INVENTION

[0061] With reference to fig. 1, a transmission system 10 according to the present invention is designed and usable to transmit and receive data D via satellite 11 , and it is dedicated and optimized for maritime applications, for the digitalization of ports and / or the autonomous navigation of means of transport 12. Preferably, the means of transport 12 can be means of naval transport, for example able to transport goods.

[0062] However, the transmission system 10 could also be associated with vessels or ships suitable to transport passengers, or possibly also be extended to other types of means of transport by land or air, in order to be able to transmit data in addition or as an alternative to those possibly provided by the respective drivers or pilots.

[0063] In addition, the transmission system 10 can be used to exchange data between maritime systems such as ports.

[0064] We must clarify that the term “transmission”, when combined with a system, a station, an assembly, means or components, indicates that these are capable of both transmitting and also receiving signals, data, information, etc.

[0065] The transmission system 10 comprises at least a first 20 and a second 30 transmission station, which can be mobile or fixed with respect to the first station 20.

[0066] For example, the first station 20 is fixed and positioned on land and the second station 30 is disposed on a corresponding means of transport 12. Alternatively, the second station 30 can also be fixed on Earth.

[0067] The data D can be transmitted unencrypted, or coded or encrypted. The data D to be transmitted unencrypted can be, for example, those relating to the position of the first 20 and second 30 station, or other basic or known information. The data D to be encrypted, on the other hand, can be, for example, data relating to the load transported, the destination point, the arrival time of the means of transport and / or the operating status of the corresponding engines or motors, or the general operating condition of the means of transport 12.

[0068] The transmission system 10 comprises at least one satellite station 40 positioned, during use, on a satellite orbiting Earth.

[0069] The satellite 11 can for example be of the type suitable to move on in orbit located at a distance of about 400-36,000 km from Earth with a speed of about 3- lO km / s.

[0070] The first 20 and second 30 station are operatively connectable to each other through at least one satellite station 40.

[0071] According to preferred embodiments, the transmission system 10 comprises several satellite stations 40 which are configured to operatively connect to and communicate with the first 20 and second 30 station.

[0072] The first station 20 comprises a respective, or first, radio frequency transmission assembly 21 configured to transmit and receive one or more radio frequency signals SR containing the data D, and a respective, or first, optical assembly 22 configured to transmit and / or receive one or more optical signals SO. Furthermore, the first station 20 also comprises a respective, or first, management and control unit 23 of the first radio frequency transmission assembly 21 and of the first optical assembly 22.

[0073] The second station 30 comprises a respective, or second, radio frequency transmission assembly 31 configured to transmit and receive one or more radio frequency signals SR containing the data D, and a respective, or second, optical assembly 32 configured to transmit and / or receive one or more optical signals SO. Furthermore, the second station 30 also comprises a respective, or second, management and control unit 33 of the second radio frequency transmission assembly 31 and of the second optical assembly 32.

[0074] Each satellite station 40 comprises a respective, or third, radio frequency transmission assembly 41 configured to transmit and receive one or more radio frequency signals SR containing the data D, and a respective, or third, optical assembly 42 configured to transmit and / or receive one or more optical signals SO.

[0075] Furthermore, each third station 40 also comprises a respective, or third, management and control unit 43 of the third radio frequency transmission assembly 41 and of the third optical assembly 42.

[0076] As will be better described below, each first station 20, second station 30 and satellite station 40 is configured to transmit and receive at least one optical pointing signal SO to establish a stable point-to-point optical connection with, respectively, the satellite station 40 or one of either the first 20 or second station 30, and possibly to transmit and / or receive an optical signal SO to allow the quantum distribution of encryption keys. We must clarify that specific radio frequency communication channels of a known type can be used to transmit the above mentioned radio frequency signals SR.

[0077] According to some embodiments, each radio frequency transmission assembly 21, 31, 41 is also configured to transmit and receive a first radio frequency signal SR, by means of which a first rough alignment is obtained between a respective first 20 or second 30 station and the corresponding satellite station 40, or vice versa.

[0078] In other words, each first station 20, second station 30 and satellite station 40 is configured to transmit and receive both one or more radio frequency signals SR containing the data D relating to the information to be exchanged and transmitted between such stations 20, 30, 40, and also one or more radio frequency pointing signals SR having the purpose of establishing a first connection with a satellite station 40 or one of either the first 20 or second station 30. Each radio frequency transmission assembly 21, 31, 41 comprises a plurality of antennas 25, 35, 45 suitably oriented in different directions so as to cover an area wide enough to allow the transmission of the radio frequency signals SR between the stations 20, 30 and the corresponding satellite station 40. The third radio frequency transmission assembly 41, being mounted on a corresponding satellite 11 in continuous motion and available for a limited time, can comprise, for example, a greater number of antennas 45 than the first 21 and second 31 radio frequency transmission assembly, since it has to be identified and connected in good time to allow the correct transmission of the data D. Furthermore, at least the third radio frequency transmission assembly 41 can also comprise one or more steerable beam antennas, not shown in the drawings, so as to facilitate the identification and connection with the first 21 and second 31 radio frequency transmission assembly.

[0079] The antennas 25, 35, 45 are able to operate in a certain frequency range and in any weather condition; therefore, they cover a wide power dynamic range.

[0080] The radio frequency transmission assemblies 21, 31, 41 also comprise a transceiver module 26, 36, 46 having an adequate frequency channelization so as to tune into different sources and frequencies.

[0081] By way of example, the antennas 25, 35, 45 can have a gain comprised in a range between about 15 dB and about 25 dB, in relation to the specific frequency band, and the transceiver module 26, 36, 46 can have a sensitivity in the range of about -80 dBm; moreover, the actual noise figure does not exceed about 3 dB.

[0082] The optical signals SO are preferably laser signals, and specific communication channels are used to transmit them. The first 22, second 32 and third 42 optical assembly are configured to transmit and / or receive at least a first type of optical signal SOI for the quantum distribution of at least one encryption key associable with the data D, to encrypt and decrypt them.

[0083] Specific quantum communication channels are used to transmit this first type of optical signal SOI .

[0084] Furthermore, we must specify that the transmission of the first type of optical signal SOI occurs only when it is necessary to implement the quantum distribution protocol of the encryption keys, while the data D encrypted with the latter are transmitted with radio frequency signals SR.

[0085] For example, the present invention can be applied to Prepare and Measure (PM) and Entanglement Based (EB) quantum key exchange protocols, known to the people of skill in the art. These protocols provide a quantum communication channel to transmit the quantum optical signals SO and a radio frequency communication channel to support the quantum distribution protocol for the generation of an encryption key.

[0086] According to preferred embodiments, an encrypted quantum key distribution protocol, also known by the acronym QKD, can be employed. Preferably, the quantum distribution protocol used can be BB84, known to the people of skill in the art. It is clear that other known protocols, or ones to be developed in the future, can be used in other embodiments.

[0087] According to preferred embodiments, at least the third optical assembly 42 is able to transmit the first type of optical signal SOI for the quantum distribution of the encryption key.

[0088] The first 22 and second 32 optical assembly, on the other hand, are able to receive the first type of optical signal SOI transmitted by the third optical assembly 42 to use it in the transmission of the data D that has to be encrypted, or respectively to decrypt the data D received. According to some embodiments, the satellite station 40 is also configured to transmit and receive, in addition to the one or more radio frequency signals SR containing the data to be exchanged and the one or more radio frequency pointing signals SR, both at least a first type of optical signal SOI to enable the quantum distribution of encryption keys, and also a second type of pointing optical signal SO2 to establish a stable point-to-point optical connection with a respective first 20 and / or second station 30.

[0089] Therefore, according to preferred embodiments, the transmission of the first type of optical signal SO 1 is unidirectional, since it occurs from the third optical assembly 42 toward the first 22 and / or the second 32 optical assembly. This allows the quantum distribution of encryption keys directly from the satellite station 40, which acts as an intermediary, ensuring that the encryption keys are shared with the first 20 and / or second 30 station, between which communication has to be established. In other words, by means of the first type of optical signal SOI, the satellite station 40 and the connected first 20 or second 30 station are able to co-generate a shared encryption key, through the generation of random bits, which is subsequently used to encrypt the data D transmitted by means of the radio frequency signal SR.

[0090] However, different embodiments could also be provided, in which the transmission of the optical signal SOI can be carried out by the first station 20, or by the second station 30. In this case, however, it is necessary to provide suitable single-photon detectors on board the corresponding satellite 11. The first 22 and second 32 optical assembly and the third optical assembly 42 are able to also transmit and receive a second type of optical pointing signal SO2, which is aligned with the first type of optical signal SOI to establish a stable point- to-point optical connection between the first 22 and second 32 optical assembly and the corresponding third optical assembly 42. In this way, a stable line of sight is guaranteed between the stations 20, 30, 40, which allows the correct transmission of the first type of optical signal SOI for the implementation of the quantum distribution protocol of the encryption keys.

[0091] Preferably, the second type of optical signal SO2 is transmitted after a first radio frequency pointing signal SR has been transmitted, by means of which a first raw and non-point alignment between the stations 20, 30, 40 is achieved, preparatory to achieving a precision alignment.

[0092] According to some embodiments, the transmission of the radio frequency pointing signal SR can be of a bidirectional type, that is, be carried out both from the third radio frequency transmission assembly 41 toward the first 21 and / or the second 31 radio frequency transmission assembly, and also from the latter toward the third radio frequency transmission assembly 41.

[0093] According to preferred embodiments, the transmission of the second type of optical signal SO2 is bidirectional, since there is both a transmission from the third optical assembly 42 toward the first 22 and / or the second 32 optical assembly, and also a transmission from the latter toward the third optical assembly 42. By way of example, the second type of optical signal SO2 can be a laser signal, also called a beacon, as known to the people of skill in the art.

[0094] The first management and control unit 23, the second management and control unit 33, and the corresponding third management and control unit 43 are operatively connectable to each other and are respectively configured and programmed to associate at least one encryption key transmitted with quantum distribution protocol with at least a part of the data D in order to encrypt them and, respectively, decrypt them when they are transmitted and, respectively, received from one station 20, 30, 40 to another.

[0095] According to preferred embodiments, the management and control units 23, 33, 43 are programmed to automatically determine whether a given datum D has to be encrypted or not. According to possible solutions, each station 20, 30, 40 can comprise a memory unit, not shown, operatively connected to the respective management and control unit 23, 33, 43, in which information relating to the operating or operational status of the means of transport 12 or of the load associated therewith, and also the types of data for which encryption is required, can be stored. According to possible preferred embodiments, each third management and control unit 43 comprises an automatic processing sub-unit 47, configured to implement, or manage, the quantum key distribution protocol and the generation of a plurality of encryption keys, making them usable for the first 23 and second 33 management and control unit. Each third management and control unit 43 also comprises at least one memory 48 in which the generated and not yet used encryption keys, or the associations between a respective key and the station 20, 30, can be stored. As the keys are gradually used, they can be erased and overwritten by the new keys on each occasion. In this way, the memory 48 can be of a small size, suitable to be installed on the satellite 11. The memory 48 is able to store a large number of encryption keys, even greater than 100,000, for example keys of the AES256 type.

[0096] In addition, in the first 20 and second 30 station there are provided respective electric management means 28, 38 connected to the first 23 and second 33 management and control unit and having a management and control interface that can possibly be commanded by a user. The electric management means 28, 38 can be on-board computers, electronic boards, microprocessors, or similar devices.

[0097] According to some embodiments, the management and control units 23, 33, 43 of the satellite station 40 and of the first and second station 20, 30 are configured and programmed to command the respective radio frequency transmission assemblies 21, 31, 41 so as to transmit or receive, respectively, a first radio frequency pointing signal SR to establish a first alignment between one of either the first 20 and / or the second station 30 and at least one satellite station 40, and then command the respective optical assemblies 22, 32, 42 to transmit and receive at least a second type of optical pointing signal SO2 to establish a stable point-to- point optical connection between the first 20 and / or the second station 30 and the corresponding satellite station 40.

[0098] The first radio frequency pointing signal SR can be transmitted bi-univocally from one of either the first 20 or the second station 30 toward the satellite station 40, or vice versa.

[0099] The optical assemblies 22, 32, 42 (fig. 2) comprise respective means 50 for generating and means 51 for propagating the optical signals SO. The generating means 50 can be disposed in dedicated protective containers. According to possible embodiments, the optical generating means 50 comprise at least one emitter, or transmitter, 55, one or more intensity modulators, preferably a pair, 56a, 56b, a phase modulator 57 and an attenuator 59 operatively connected to each other.

[0100] By way of example, the emitter 55 uses weak coherent states with time-bin encoding and is able to operate at 100 MHz. The optical signals SO emitted are defined by continuous waves having a wavelength suitable for transmission through the atmosphere.

[0101] The term “time-bin encoding” refers to a technique used in quantum information science to encode a basic unit of quantum information on a photon. The intensity modulators 56a, 56b comprise a first modulator 56a able to provide a pulse train, and a second modulator 56b able to modify the intensity of such pulses in two different values, specifically a recall state and a signal state.

[0102] The phase modulator 57 is able to perform a phase randomization of each state, in order to obtain time-bin pulses with random phases. The attenuator 59 is of the variable optical type and is able to attenuate the intensities of such pulses in order to reach a single-photon regime, so that the first type of optical signal SOI is correctly prepared to be transmitted through the atmosphere by means of the propagation means 51. Furthermore, the generating means 50 are connected to a programmable integrated circuit 60 and to a microcontroller 61, which have the function of coordinating the operation of the generating means 50 with respect to the operation of the corresponding radio frequency transmission assembly 21, 31, 41. According to possible embodiments, the programmable integrated circuit 60 and the microcontroller 61 can be connected to, or form part of, the corresponding management and control unit 23, 33, 43.

[0103] According to possible embodiments, the optical propagation means 51 can comprise a main lens 63, a rapid orientation mirror 64 and a dichroic filter 65 to direct the optical signals SO to a camera 66 and to a dedicated telescope 67, which allow the transmission of the optical signals SO through the atmosphere, from one station 20, 30, 40 to another.

[0104] The first 22 and second 32 optical assembly can also comprise respective optical detector members 27, 37 which are configured to detect at least the first type of optical signal SOI and which are connected to the electronic devices 28, 38.

[0105] According to preferred embodiments, the detector members 27, 37 can be superconducting nanowire single-photon detectors (SNSPDs) able to detect quantum signals.

[0106] According to other embodiments, not shown, the third optical assembly 42 can also be provided with detector members, the same as the first 22 and second 32 optical assembly, to guarantee a quantum key distribution protocol of the upstream type, known to the people of skill in the art.

[0107] The transmission system 10 (fig. 1) is advantageously able to transmit the data D in three different modes: - a first, more secure mode, in which each individual exchange of data D takes place with an associated encryption key which is distributed with quantum distribution protocol, therefore for each communication / transmission of data D a new encryption key is exchanged, wherein this key has the same byte size as the transmitted data D (one-time-pad scheme known to the people of skill in the art); - a second mode, in which the encryption key is distributed, with quantum distribution protocol, periodically and is used to encrypt communications subsequent to this exchange using a standard security protocol, for example AES (Advanced Encryption Standard), until a new encryption key distributed with quantum distribution protocol is available;

[0108] - a third mode, in which an asymmetric encryption key is used to encrypt the data D, therefore not using the keys distributed with a quantum distribution protocol. This advantageously allows to select the most suitable mode of transmission in relation to the importance of the datum D transmitted.

[0109] The operation of the transmission system 10 described heretofore, which corresponds to the method according to the present invention, comprises the following steps. In a waiting step, the first station 20 or the second station 30 are waiting to establish a connection with a satellite 11 provided with a satellite station 40 in order to begin the transmission of data D.

[0110] In a subsequent radio frequency connection step, the first 21 or second 31 radio frequency transmission assembly transmits, by means of the transceiver modules 26 or 36, a first radio frequency signal SR to connect together the antennas 25 or

[0111] 35 with the antennas 45 present in the third radio frequency transmission assembly 41. For example, an IP protocol with the destination IP address can be generated to establish the connection.

[0112] It is clear that the radio frequency connection between the third radio frequency transmission assembly 41 and the other of either the second 31 or the first 21 radio frequency transmission assembly is established with the same modes.

[0113] In this way, it is possible to transmit and / or receive the data D, in particular those data that can be transmitted unencrypted and do not need to be encrypted

[0114] According to preferred embodiments, an optical connection step can also be provided in which, in a succession of operating sub-steps, the optical assemblies 22, 32, 42 transmit and receive the second type of optical pointing signal SO2 in order to establish a stable point-to-point optical connection between the first 20 or second 30 station with the corresponding satellite station 40.

[0115] Through this stable optical connection it is possible to perform a correct transmission of the first type of optical signal SO 1 which allows the satellite station 40 and the connected first 20 or second 30 station to co-generate a shared encryption key to be associated with the data D to be encrypted and / or decrypted.

[0116] A sufficient number of encryption keys can already be stored in the memory 48. Furthermore, the processing sub-unit 47 present in each third management and control unit 43 can generate at least one encryption key at a time according to the quantum key distribution protocol.

[0117] In a first transmission step, the third optical assembly 42 transmits the first type of optical signal SOI toward the first 22 or second 32 optical assembly, for the cogeneration of at least one encryption key shared between the satellite station 40 and the first 20 or second 30 station.

[0118] The transmission and reception of the optical signals SO is performed by means of the generating means 50 and the propagation means 51 (fig. 2). Then, in a first processing step, the first 23 or second 33 management and control unit associates the encryption key distributed with quantum distribution protocol with a part of the data D to be encrypted, which are subsequently transmitted via the first 21 or second 31 radio frequency transmission assembly. We must clarify that, in this step, the destination address relating to the radio frequency transmission assembly 31, 21 toward which the encrypted data D is to be transmitted is also encrypted.

[0119] Subsequently, in a first communication step, the encrypted data D is transmitted from the first 21 or second 31 radio frequency transmission assembly toward the third transmission assembly 41. According to some embodiments, in the satellite station 43 the data D is decrypted so as to identify the destination address.

[0120] Then, in a second processing step, the third management and control unit 43 associates a new encryption key distributed with quantum distribution protocol with the data D. In a subsequent second transmission step, the third optical assembly 42 transmits another first type of optical signal SOI toward the second 32 or first 22 optical assembly, to make the new encryption key usable by or available to the second 30 or first 20 station.

[0121] Subsequently, in a second processing step, the second 33 or first 23 management and control unit uses the new encryption key to decrypt the data D received, thus obtaining information able to allow a correct and safe autonomous navigation of the means of transport 12.

[0122] We must clarify that the connection, transmission, processing and communication steps can be carried out cyclically to allow the correct transmission of the data D.

[0123] It is clear that modifications and / or additions of parts may be made to the transmission system 10 and to the method as described heretofore, without thereby departing from the field and scope of the present invention, as defined by the claims.

[0124] It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art will be able to create other equivalent forms of data transmission systems, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

[0125] In the following claims, the sole purpose of the references in brackets is to facilitate their reading and they must not be considered as restrictive factors with regard to the field of protection defined by the claims.

Claims

CLAIMS1. Data (D) transmission system (10) via satellite (11), comprising at least one satellite station (40) disposed on a respective satellite (11), at least a first transmission station (20) and a second transmission station (30) which are configured to communicate, during use, with said at least one satellite station (40), characterized in that at least one of said first (20) and second station (30) is disposed, during use, on a mobile means of transport (12), the other being disposed on a respective mobile means of transport (12) or on a fixed point on land, and in that said stations (20, 30, 40) each comprise: at least a transmission assembly (21, 31, 41) configured to transmit and receive one or more radio frequency signals (SR) containing said data (D), an optical transmission assembly (22, 32, 42) configured to transmit and / or receive one or more optical signals (SO) comprising at least a first type of optical signal (SOI) to allow the quantum distribution of encryption keys, and a management and control unit (23, 33, 43) of said radio frequency transmission assembly (21, 31, 41) and of said optical assembly (22, 32, 42), said management and control unit (23, 33, 43) being configured and programmed to associate said at least one encryption key with at least a part of said data (D) in order to encrypt them and, respectively, decrypt them when they are transmitted and received from one of said stations (20, 30, 40) to another, wherein said management and control units (23, 33, 43) of said at least one satellite station (40) and said first and second station (20, 30) are configured and programmed to command the respective radio frequency transmission assemblies (21, 31, 41) so as to transmit or receive, respectively, a first radio frequency pointing signal (SR) to establish a first alignment between one of said first and / or second station (20, 30) and said at least one satellite station (40), and subsequently command said respective optical assemblies (22, 32, 42) to transmit and receive at least a second type of optical pointing signal (SO2), in order to establish a stable point-to-point optical connection between said first and / or second station (20, 30) and said at least one corresponding satellite station (40).

2. Transmission system (10) as in claim 1, characterized in that said first station (20) is disposed, during use, on a naval means of transport (12).

3. Transmission system (10) as in any claim hereinbefore, characterized in that through the transmission of said first type of optical signal (SOI), said satellitestation (40) and the connected first (20) or second (30) station are able to cogenerate an encryption key subsequently used to encrypt or decrypt said data (D).

4. Transmission system (10) as in any claim from 1 to 3, characterized in that each one of said optical assemblies (22, 32, 42) is configured to transmit and receive said second type of pointing optical signal (SO2), spatially aligned with said first type of optical signal (SOI) to establish said stable point-to-point optical connection between said first (20) or second (30) station and the corresponding satellite station (40), or vice versa, wherein the transmission of said first type of optical signal (SOI) is unidirectional, from said satellite station (40) toward one or each of said first and second station (20, 30), and wherein the transmission of said second type of optical signal (SO2) is bidirectional, from said satellite station (40) toward said first (20) and / or second station (30), and vice versa.

5. Transmission system (10) as in any claim hereinbefore, characterized in that each satellite station (40) comprises a third management and control unit (43) provided with at least one automatic processing sub-unit (47) configured to implement and / or manage the quantum key distribution protocol and the generation of encryption keys able to be stored in a memory (48), or transmitted one at a time together with said encrypted data (D) by means of said radio frequency signal (SR), in order to thus make them usable for the respective first (23) and / or second (33) management unit of said first and second station (20, 30).

6. Transmission system (10) as in any claim hereinbefore, characterized in that in said first (20) and second (30) station there are provided respective electric management means (28, 38) connected to said first (23) and second (33) management and control unit, respectively, and having a management interface able to be commanded by a user.

7. Transmission system (10) as in any claim hereinbefore, characterized in that each radio frequency transmission assembly (21, 31, 41) comprises at least a plurality of antennas (25, 35, 45) suitably oriented in such a way as to cover a suitable area to allow the correct transmission of said radio frequency signals (SR), and at least one transceiver module (26, 36, 46) having an adequate frequency channeling so that it can be tuned in to different sources and frequencies.

8. Transmission system (10) as in any claim hereinbefore, characterized in that it comprises a plurality of satellite stations (40) installed on respective satellitesplaced in orbit and a plurality of first transmission stations (20) each disposed, during use, on a respective moving naval means of transport (12).

9. Data (D) transmission method via satellite (11) executed by means of a transmission system (10) comprising at least one satellite station (40) disposed on a respective satellite (11) and operationally connected to a first transmission station(20) and to a second transmission station (30) which are configured to communicate, during use, with said at least one satellite station (40), characterized in that at least said first station (20) is disposed on a mobile means of transport (12) and said second station (30) is disposed on another mobile means of transport (12) or on a fixed point on land, and said method comprises one or more operating steps in which respective radio frequency transmission assemblies (21, 31, 41) of said first and second station (20, 30) and of said satellite station (40) transmit and receive one or more radio frequency signals (SR) containing said data (D), in which respective ones of said optical assemblies (22, 32, 42) transmit and / or receive one or more optical signals (SO) comprising at least a first type of optical signal (SOI) for the quantum distribution of encryption keys, and in which said respective management and control units (23, 33, 43) associate said at least one encryption key with at least a part of said data (D) to encrypt and decrypt them when they are transmitted and received, respectively, from one station (20, 30, 40) to another, in which said radio frequency transmission assemblies (21, 31, 41) of at least two of said stations (20, 30, 40) transmit and / or receive a first radio frequency pointing signal (SR) to establish a first alignment between them, and, subsequently, said respective optical assemblies (22, 32, 42) also transmit and receive at least a second type of pointing optical signal (SO2), which is aligned with the radio frequency pointing signal (SR), with which said first type of optical signal (SOI) is subsequently aligned, to establish a stable point-to-point optical connection between said first and / or second station (20, 30) and a corresponding satellite station (40).

10. Transmission method as in claim 9, characterized in that by transmitting said first type of optical signal (SOI), said satellite station (40) and the connected first (20) or second (30) station co-generate an encryption key subsequently used to encrypt, or decrypt, said data (D).

11. Transmission method as in claim 9 or 10, characterized in that said firsttype of optical signal (SOI) is transmitted in a unidirectional manner from said satellite station (43) toward said first (20) or second (30) station, and wherein said second type of optical signal (SO2) is transmitted in a bidirectional manner, from said satellite station (40) toward said first (20) and / or second (30) station, and vice versa.

12. Transmission method as in any claim from 9 to 11, characterized in that a processing sub-unit (47) of said management and control unit (43) manages the quantum distribution protocol of encryption keys which are stored in a memory (48), or transmitted one at a time together with said encrypted data (D) by means of said radio frequency signal (SR), in order to thus make them usable for the respective first (23) and / or second (33) management unit of said first and second station (20, 30).

13. Transmission method as in any claim from 9 to 12, characterized in that said data (D) are transmitted through said one or more radio frequency signals (SR) according to at least a first mode, in which each data (D) transmission occurs with an associated encryption key distributed with quantum distribution protocol.

14. Transmission method as in any claim from 9 to 13, characterized in that said data (D) are transmitted through said one or more radio frequency signals (SR) according to at least a second mode, in which an encryption key is distributed with quantum distribution protocol periodically and is used to encrypt communications which follow said distribution using a standard security protocol until a new encryption key distributed with quantum distribution protocol is available.

15. Transmission method as in any claim from 9 to 14, characterized in that said data (D) are transmitted through said one or more radio frequency signals (SR) according to at least a third mode, in which said data (D) are encrypted with an asymmetric encryption key using a communication channel without the use of encryption keys distributed with quantum distribution protocol.

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